[tip: irq/urgent] irqchip/gic-v2m: Prevent use after free of gicv2m_get_fwnode()

[tip-bot2 for Suzuki K Poulose]

The following commit has been merged into the irq/urgent branch of tip:

Commit-ID:     be5413232123b7700df856cbfd20cfa528b4f132
Gitweb:        https://git.kernel.org/tip/be5413232123b7700df856cbfd20cfa528b4f132
Author:        Suzuki K Poulose <suzuki.poulose@xxxxxxx>
AuthorDate:    Tue, 22 Apr 2025 17:16:16 +01:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Thu, 24 Apr 2025 14:28:52 +02:00

irqchip/gic-v2m: Prevent use after free of gicv2m_get_fwnode()

With ACPI in place, gicv2m_get_fwnode() is registered with the pci
subsystem as pci_msi_get_fwnode_cb(), which may get invoked at runtime
during a PCI host bridge probe. But, the call back is wrongly marked as
__init, causing it to be freed, while being registered with the PCI
subsystem and could trigger:

 Unable to handle kernel paging request at virtual address ffff8000816c0400
  gicv2m_get_fwnode+0x0/0x58 (P)
  pci_set_bus_msi_domain+0x74/0x88
  pci_register_host_bridge+0x194/0x548

This is easily reproducible on a Juno board with ACPI boot.

Retain the function for later use. 

Fixes: 0644b3daca28 ("irqchip/gic-v2m: acpi: Introducing GICv2m ACPI support")
Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Marc Zyngier <maz@xxxxxxxxxx>
Cc: linux-stable@xxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/all/20250422161616.1584405-1-suzuki.poulose@xxxxxxx
Link: https://lkml.kernel.org/r/68053cf43bb54_7205294cc@xxxxxxxxxxxxxxxxxxxxxxxxx.notmuch
---
 drivers/irqchip/irq-gic-v2m.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-gic-v2m.c b/drivers/irqchip/irq-gic-v2m.c
index c698948..dc98c39 100644
--- a/drivers/irqchip/irq-gic-v2m.c
+++ b/drivers/irqchip/irq-gic-v2m.c
@@ -421,7 +421,7 @@ static int __init gicv2m_of_init(struct fwnode_handle *parent_handle,
 #ifdef CONFIG_ACPI
 static int acpi_num_msi;
 
-static __init struct fwnode_handle *gicv2m_get_fwnode(struct device *dev)
+static struct fwnode_handle *gicv2m_get_fwnode(struct device *dev)
 {
 	struct v2m_data *data;